JP5944852B2 - Sealing structure - Google Patents

Description

  The present invention relates to a sealing structure including a tandem mechanical seal.

  There is known a tandem type mechanical seal that uses two mechanical seals, has two seal end faces, and each mechanical seal faces the same direction. In such mechanical seals, for pharmaceutical and food applications, it is generally necessary to periodically clean the sliding portion between the seal end surface on the rotating ring side and the seal end surface on the stationary ring side. However, in the case of a mechanical seal, since the rotating ring and the stationary ring are pressed by a spring or the like, it is usually necessary to disassemble the apparatus when cleaning the sliding portion. Therefore, it takes time for the cleaning work. Moreover, in order to save the effort which decomposes | disassembles an apparatus, the technique provided with the mechanism in which a rotating ring and a fixed ring are spaced apart is also known, However, There exists a fault which a structure becomes complicated (refer patent document 1). Furthermore, in such a technique, when the cleaning fluid remains between the rotating ring and the stationary ring, it is difficult to discharge, and the sealing performance may be adversely affected. In addition, there exists a technique disclosed by patent document 2 as another related technique. However, this document does not describe any cleaning.

JP 2010-65555 A JP-A-6-17941

  An object of the present invention is to provide a sealing structure that enables simple cleaning operations with a simple structure.

  The present invention employs the following means in order to solve the above problems.

That is, the sealing structure of the present invention is
A first mechanical seal and a second mechanical seal each facing in the same direction, and when operating, when purge gas is supplied to a region between the first mechanical seal and the second mechanical seal and is not operating A sealing structure including a tandem mechanical seal configured to be able to supply a cleaning fluid to the region,
Among the seal end faces of the rotary ring in the first mechanical seal, the inner peripheral surface side, which is the region side, generates a dynamic pressure along with the rotation of the rotary ring, thereby generating a seal end face of the fixed ring in the first mechanical seal. A plurality of first spiral grooves for generating a gap between them are provided at intervals in the circumferential direction, and the groove depth is shallower than the first spiral groove between the adjacent first spiral grooves. Constituted by the second helical groove,
Among the seal end faces of the rotating ring in the second mechanical seal, the outer peripheral surface side which is the region side is in contact with the seal end face of the stationary ring in the second mechanical seal by generating dynamic pressure along with the rotation of the rotating ring. A plurality of third spiral grooves for generating a gap therebetween are provided at intervals in the circumferential direction, and a gap between the adjacent third spiral grooves is shallower than the third spiral groove. It is characterized by comprising four spiral grooves.

According to the present invention, the inner peripheral surface side of the seal end surface of the rotary ring in the first mechanical seal is constituted by the first spiral groove and the second spiral groove. Moreover, the outer peripheral surface side is comprised by the 3rd spiral groove and the 4th spiral groove among the seal end surfaces of the rotary ring in a 2nd mechanical seal. Thus, by supplying the cleaning fluid to the region between the first mechanical seal and the second mechanical seal, the cleaning fluid can be sent to the seal end face of each mechanical seal via these spiral grooves. It becomes possible. Therefore, the seal end face can be cleaned without disassembling the mechanical seal.

  Each mechanical seal includes not only a groove for generating dynamic pressure (first spiral groove and third spiral groove) but also a shallower groove (second spiral groove and fourth spiral). Shaped groove). For this reason, it is possible to improve the discharge performance of the cleaning fluid. Thereby, at the time of washing | cleaning, it can make it easy to supply the fluid for washing | cleaning to the seal | sticker end surface of each mechanical seal. Even if the cleaning fluid remains in the spiral groove, the cleaning fluid can be immediately discharged from the spiral groove by rotating the rotating ring during the subsequent operation.

  As described above, according to the present invention, the cleaning operation can be easily performed with a simple structure.

FIG. 1 is a schematic cross-sectional view of a sealing structure according to an embodiment of the present invention. FIG. 2 is a front view of the seal end face in the rotary ring of the first mechanical seal according to the embodiment of the present invention. FIG. 3 is a partially broken sectional view of the rotary ring of the first mechanical seal according to the embodiment of the present invention. FIG. 4 is a front view of the seal end face of the rotary ring of the second mechanical seal according to the embodiment of the present invention. FIG. 5 is a partially broken sectional view of the rotary ring of the second mechanical seal according to the embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

(Example)
With reference to FIGS. 1-5, the sealing structure which concerns on the Example of this invention is demonstrated. In the present embodiment, a sealing structure that seals an annular gap between a rotating shaft for rotating a stirring blade for stirring and a housing in the stirrer will be described as an example.

<Entire sealing device>
In particular, with reference to FIG. 1, the overall structure of the sealing structure according to the embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view of a sealing structure according to an embodiment of the present invention. In addition, the cross-sectional view in FIG. 1 is a cross-sectional view including the central axis of the mechanical seal and the rotation shaft. Further, various members constituting the sealing structure according to the present embodiment are annular members except for springs 140 and 230 and pins 150 and 250 described later.

The sealing structure according to the present embodiment is provided in an agitator to seal an annular gap between a rotating shaft 300 that rotates a stirring blade (not shown) and a housing 400 having a shaft hole of the rotating shaft 300. This sealing structure is provided in the upper part of the stirring kiln 500 in the installed state.
In FIG. 1, (A) is the atmosphere side, and (B) is the inner side of the stirring kiln 500. A stirring blade (not shown) is provided below the rotary shaft 300.

  The sealing structure according to the present embodiment includes a tandem mechanical seal. Here, the tandem type is a system that uses two mechanical seals and has two seal end faces, and each mechanical seal faces the same direction (rotating ring and fixed ring are provided in the same order in the axial direction) Structure). In the present embodiment, the first mechanical seal 100 is provided on the upper side (atmosphere side), and the second mechanical seal 200 is provided on the lower side (inside the kiln).

  In this embodiment, in order to protect the rotating shaft 300, a first sleeve 310 is attached to the outer periphery of the rotating shaft 300, and a second sleeve 320 is attached to the outer periphery of the first sleeve 310. An annular gap between these sleeves and the housing 400 fixed to the stirring furnace 500 is sealed by the first mechanical seal 100 and the second mechanical seal 200.

  The housing 400 includes a housing main body 410 and a flange 420 fixed between the housing main body 410 and the stirring kiln 500. Drain passages 412 and 421 are formed in the housing body 410 and the flange 420, respectively. In addition, a supply passage 411 for supplying purge gas to a region R between the first mechanical seal 100 and the second mechanical seal 200 is formed in the housing main body 410.

  The first mechanical seal 100 is provided on the rotary ring 110 fixed to the first sleeve 310, and is slidable with respect to the rotary ring 110, and is provided on the case 130 side fixed to the inner peripheral surface of the housing 400. A ring 120 and a spring 140 that urges the stationary ring 120 toward the rotating ring 110 are provided. Here, the rotating ring 110 is configured not to rotate with respect to the rotating shaft 300, and the fixed ring 120 is configured not to rotate with respect to the housing 400. More specifically, the rotating ring 110 is configured not to rotate with respect to the second sleeve 320 by the pin 150 fixed to the second sleeve 320, so that it does not rotate with respect to the rotating shaft 300. It has become. Further, the fixed ring 120 is configured not to rotate with respect to the housing main body 410 by a pin (not shown), so that it does not rotate with respect to the housing 400.

  With the above configuration, the rotating ring 110 rotates with the rotation of the rotating shaft 300, and the stationary end ring 120 that is stationary and the seal end surfaces of the rotating rotating ring 110 slide. Further, since the fixed ring 120 is urged toward the rotating ring 110 by the spring 140, the fixed ring 120 and the rotating ring 110 are kept in a sliding state.

  The second mechanical seal 200 includes a rotating ring 210 fixed to the first sleeve 310, a slidable arrangement with respect to the rotating ring 210, and a fixed ring 220 provided on the housing body 410 side, and the fixed ring 220 rotating. A spring 230 and a compression ring 240 that urge toward the ring 210 side are provided. Here, the rotating ring 210 is configured not to rotate with respect to the rotating shaft 300, and the fixed ring 220 is configured not to rotate with respect to the housing 400. More specifically, the rotation ring 210 is configured not to rotate with respect to the second sleeve 320 by the pin 250 fixed to the second sleeve 320, so that the rotation ring 210 does not rotate with respect to the rotation shaft 300. It has become. Further, the fixed ring 220 is configured not to rotate with respect to the housing main body 410 by a pin (not shown), so that it does not rotate with respect to the housing 400.

With the above configuration, the rotating ring 210 rotates with the rotation of the rotating shaft 300, and the stationary end ring 220 in a stationary state and the seal end surfaces of the rotating rotating ring 210 slide. Further, since the fixed ring 220 is urged toward the rotating ring 210 by the spring 230 and the compression ring 240, the fixed ring 220 and the rotating ring 210 are kept in a sliding state.

  In the sealing structure, a plurality of fixtures (not shown) such as bolts and set screws are provided to fix the members to each other. Since the fixing tool is a known technique, its description is omitted. Further, the sealing structure is provided with a plurality of O-rings O in order to seal the gaps between the members. Since the O-ring O is also a known technique, the description thereof is omitted.

<Rotating ring>
In particular, the rotating ring according to the embodiment of the present invention will be described in more detail with reference to FIGS. FIG. 2 is a front view of the seal end face in the rotary ring of the first mechanical seal according to the embodiment of the present invention. FIG. 3 is a partially broken sectional view of the rotary ring of the first mechanical seal according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of a part of the rotary ring of the first mechanical seal taken along a plane including the central axis of the rotary ring. FIG. 4 is a front view of the seal end face of the rotary ring of the second mechanical seal according to the embodiment of the present invention. FIG. 5 is a partially broken sectional view of the rotary ring of the second mechanical seal according to the embodiment of the present invention. FIG. 5 is a cross-sectional view of a part of the rotary ring of the second mechanical seal taken along a plane including the central axis of the rotary ring.

  First, the rotating ring 110 in the first mechanical seal 100 will be described with reference to FIGS. 2 and 3. A plurality of first spiral grooves 111a are provided on the inner peripheral surface side (region (R) side) of the seal ring end surface of the rotating ring 110 at intervals in the circumferential direction. The plurality of first spiral grooves 111a are configured to extend from the outer peripheral surface side to the inner peripheral surface side in the rotational direction X of the rotary ring 110. Moreover, between each adjacent 1st spiral groove 111a, it is comprised by the 2nd spiral groove 111b whose groove depth is shallower than the 1st spiral groove 111a. That is, the first spiral groove 111a and the second spiral groove 111b are alternately provided on the inner peripheral surface side of the seal end surface of the rotating ring 110. Here, both the first spiral groove 111a and the second spiral groove 111b are configured so that the width gradually decreases toward the outer peripheral surface side in the vicinity of the distal end on the outer peripheral surface side (FIG. 2). reference).

  In the present embodiment, the thickness of the rotating ring 110 is about 10 mm, whereas the depth of the first spiral groove 111a is about 10 μm or more and 40 μm or less, and the depth of the second spiral groove 111b is 2 μm. It is set to about 10 μm or less. In addition, slits 112 into which pins 150 are inserted are provided in two locations near the inner peripheral end face of the rotating ring 110.

  Next, the rotating ring 210 in the second mechanical seal 200 will be described with reference to FIGS. 4 and 5. A plurality of third spiral grooves 211a are provided on the outer peripheral surface side (region (R) side) of the seal ring end surface of the rotating ring 210 at intervals in the circumferential direction. The plurality of third spiral grooves 211a are configured to extend from the inner peripheral surface side to the outer peripheral surface side in the rotational direction X of the rotary ring 210. Further, a space between each adjacent third spiral groove 211a is configured by a fourth spiral groove 211b having a groove depth shallower than that of the third spiral groove 211a. That is, the third spiral groove 211a and the fourth spiral groove 211b are alternately provided on the outer peripheral surface side of the seal end surface of the rotating ring 210. Here, each of the third spiral groove 211a and the fourth spiral groove 211b is configured such that the width gradually decreases toward the inner peripheral surface side in the vicinity of the tip on the inner peripheral surface side ( (See FIG. 4).

In this embodiment, the thickness of the rotating ring 210 is about 10 mm, whereas the depth of the third spiral groove 211a is about 10 μm to 40 μm and the depth of the fourth spiral groove 211b is 2 μm. It is set to about 10 μm or less. Further, in the vicinity of the inner peripheral end face of the rotating ring 210, slits 212 into which the pins 250 are inserted are provided at two places.

<Mechanism during operation>
While the stirrer is operating, the rotating ring 110 in the first mechanical seal 100 and the rotating ring 210 in the second mechanical seal 200 rotate together with the rotating shaft 300. A purge gas (such as nitrogen gas) is supplied from the supply passage 411 into the region R.

  Here, the inner peripheral surface side of the seal end surface of the rotary ring 110 in the first mechanical seal 100 is configured to extend from the outer peripheral surface side to the inner peripheral surface side in the rotational direction X of the rotary ring 110. A plurality of one spiral grooves 111a are provided at intervals in the circumferential direction. As a result, dynamic pressure is generated by the airflow flowing from the inner peripheral surface side toward the outer peripheral surface side along the first spiral groove 111a while the rotating ring 110 is rotating. Therefore, the stationary ring 120 in the first mechanical seal 100 moves in a direction away from the rotating ring 110 against the urging force of the spring 140. As described above, since the minute gap is formed between the seal end surface of the rotating ring 110 and the seal end surface of the stationary ring 120 while the rotating ring 110 is rotating, sliding wear of these seal end surfaces is suppressed. Is done.

  A third spiral configured to extend from the inner peripheral surface side to the outer peripheral surface side in the rotational direction X of the rotary ring 210 on the outer peripheral surface side of the seal end surface of the rotary ring 210 in the second mechanical seal 200. A plurality of shaped grooves 211a are provided at intervals in the circumferential direction. As a result, dynamic pressure is generated by the airflow flowing from the outer peripheral surface side toward the inner peripheral surface side along the third spiral groove 211a while the rotating ring 210 is rotating. Therefore, the stationary ring 220 in the second mechanical seal 200 moves in a direction away from the rotating ring 210 against the urging force of the spring 230. As described above, since the minute gap is formed between the seal end surface of the rotary ring 210 and the seal end surface of the fixed ring 220 while the rotary ring 210 is rotating, sliding wear of these seal end surfaces is suppressed. Is done.

<Washing>
The washing of the stirrer will be described. Washing of the stirrer is performed by spraying cleaning steam as a cleaning fluid to each part with a predetermined pressure in a state where the stirrer is stopped (a state where the rotating shaft 300 is stationary).

  In the cleaning of the sealing structure portion according to the present embodiment, the cleaning is performed without disassembling the mechanical seal or the like. That is, in this embodiment, cleaning steam is supplied from the supply passage 411 formed in the housing body 410 into the region R described above at a predetermined pressure. Thereby, not only the site | part exposed to the area | region R but the seal end surface in each mechanical seal is wash | cleaned.

  That is, in the first mechanical seal 100, cleaning steam is supplied from the region R side (inner peripheral surface side) to the outer peripheral surface side through the first spiral groove 111a and the second spiral groove 111b. Here, since both the first spiral groove 111a and the second spiral groove 111b have a step with respect to the seal surface, there is a gap between the opposing fixed ring 120. Therefore, even if the original pressure of the cleaning steam is not so high, the cleaning steam is also supplied to a portion on the outer peripheral surface side where the first spiral groove 111a and the second spiral groove 111b are not provided. As described above, the entire seal end surface of the rotating ring 110 and the seal end surface of the stationary ring 120 are cleaned.

Further, in the second mechanical seal 200, cleaning steam is supplied from the region R side (outer peripheral surface side) to the inner peripheral surface side through the third spiral groove 211a and the fourth spiral groove 211b. Here, since both the third spiral groove 211a and the fourth spiral groove 211b have a step with respect to the seal surface, there is a gap between the fixed ring 220 and the opposite. Therefore, even if the original pressure of the cleaning steam is not so high, the cleaning steam is also supplied to the portion on the inner peripheral surface side where the third spiral groove 211a and the fourth spiral groove 211b are not provided. As described above, the entire seal end face of the rotating ring 210 and the seal end face of the fixed ring 220 are cleaned.

  The washed liquid, dust, and the like flow downward due to gravity, and are discharged out of the apparatus from the supply passage 411 and the drain passage 421. And after washing | cleaning a sealing structure part, the inside of the stirring kiln 500 is also wash | cleaned by washing | cleaning steam.

<Excellent point of sealing structure according to this embodiment>
According to the sealing structure according to the present embodiment, the inner peripheral surface side of the seal end surface of the rotary ring 110 in the first mechanical seal 100 is configured by the first spiral groove 111a and the second spiral groove 111b. Further, the outer peripheral surface side of the seal end surface of the rotary ring 210 in the second mechanical seal 200 is constituted by a third spiral groove 211a and a fourth spiral groove 211b. Thereby, by supplying the cleaning fluid (cleaning steam) to the region R between the first mechanical seal 100 and the second mechanical seal 200, the seal end surface of each mechanical seal is passed through these spiral grooves. It becomes possible to feed the cleaning fluid. Therefore, the seal end face can be cleaned without disassembling the mechanical seal.

  In addition, the first mechanical seal 100 and the second mechanical seal 200 include not only the spiral grooves for generating dynamic pressure (the first spiral groove 111a and the third spiral groove 211a) but also the depth of the grooves. Shallow spiral grooves (second spiral groove 111b and fourth spiral groove 211b) are provided. Therefore, the groove portion becomes a passage for the cleaning fluid, and the cleaning steam can be improved. Thereby, at the time of washing | cleaning, it can be made easy to supply washing | cleaning steam to the seal | sticker end surface of each mechanical seal. Further, even if the cleaned liquid remains in the spiral groove, the cleaned liquid can be immediately discharged from the spiral groove by rotating the rotating rings 110 and 210 during the subsequent operation. .

  In addition, since the cleaning fluid flows between the two mechanical seals of the first mechanical seal 100 and the second mechanical seal 200, the pressure of the cleaning fluid can be set high, and the cleaning fluid is more reliably applied to the seal surface. Can be distributed.

DESCRIPTION OF SYMBOLS 100 1st mechanical seal 110 Rotary ring 111a 1st spiral groove 111b 2nd spiral groove 112 Slit 120 Fixed ring 130 Case 140 Spring 150 Pin 200 2nd mechanical seal 210 Rotary ring 211a 3rd spiral groove 211b 4th spiral form Groove 212 Slit 220 Fixed ring 230 Spring 240 Compression ring 250 Pin 300 Rotating shaft 310 First sleeve 320 Second sleeve 400 Housing 410 Housing body 411 Supply passage 412 Drain passage 420 Flange 421 Drain passage 500 Stirring furnace O O-ring R region X rotation direction

Claims (1)

A first mechanical seal and a second mechanical seal, each facing in the same direction, and when operating, when purge gas is supplied to the region between the first mechanical seal and the second mechanical seal and is not operating A sealing structure including a tandem mechanical seal configured to be able to supply a cleaning fluid to the region,
Among the seal end faces of the rotary ring in the first mechanical seal, the inner peripheral surface side, which is the region side, generates a dynamic pressure along with the rotation of the rotary ring, thereby generating a seal end face of the fixed ring in the first mechanical seal. A plurality of first spiral grooves for generating a gap between them are provided at intervals in the circumferential direction, and the groove depth is shallower than the first spiral groove between the adjacent first spiral grooves. Constituted by the second helical groove,
Among the seal end faces of the rotating ring in the second mechanical seal, the outer peripheral surface side which is the region side is in contact with the seal end face of the stationary ring in the second mechanical seal by generating dynamic pressure along with the rotation of the rotating ring. A plurality of third spiral grooves for generating a gap therebetween are provided at intervals in the circumferential direction, and a gap between the adjacent third spiral grooves is shallower than the third spiral groove. A sealing structure comprising four spiral grooves.

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